Innovative dengue vaccine successfully tested

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The tiger mosquito is one of the vectors of dengue fever. Image from WikiImages
The tiger mosquito is one of the vectors of dengue fever. Image from WikiImages | Pixabay

Unisanté (University of Lausanne) has conducted a clinical study on a new type of vaccine that induces cellular immunity to combat dengue fever. The results have just been published in The Lancet eBioMedicine. They are positive and encourage further investigation. This approach is also promising for other diseases.

A global public health priority

Global warming and urbanization facilitate the spread of the tiger mosquito, responsible for dengue fever. The WHO estimates that almost half the world’s population now lives in high-risk areas. Cases of dengue fever have increased eightfold in 20 years, leading to one hospitalization per minute and two deaths per hour. An effective vaccine is therefore a priority for global health.

Two dengue vaccines are currently available in Europe, but they are proving unsatisfactory in terms of safety and efficacy. Their technology is based on the production of antibodies which, in certain cases, can increase the severity of the disease when infected by the natural virus. Unisanté has evaluated the safety and immune response of a potential dengue vaccine (PepGNP Dengue), designed using an innovative technology to induce cellular immunity without stimulating antibody production.

New approach and nano-innovations

The vaccine tested, PepGNP-Dengue, was developed in the UK by Emergex Vaccines. It consists of a nanodose of synthetic fragments of the virus, fused to gold nanoparticles. Another special feature is that it is administered under the skin via a microneedle. The vaccine relies on T lymphocytes, responsible for cellular immunity, to eliminate virus-infected cells and prevent replication.

In order to assess the safety of this first-in-human vaccine, Emergex Vaccines chose Unisanté to conduct the clinical study, given the institution’s accumulated experience in evaluating vaccine candidates against Ebola and malaria in particular. The aim of phase 1 was to determine whether the vaccine did not induce severe adverse side effects in non-diseased volunteers.

26 participants aged 18 to 45 were vaccinated in Lausanne in 2021, and followed for six months until March 2022. The results of this clinical study, supervised by Blaise Genton, Honorary Professor at the University of Lausanne, and coordinated by Alix Miauton, Research Associate at Unisanté, were published in January 2024 in the journal The Lancet eBioMedicine.

Positive results with no side effects

During the trial, no serious adverse events related to the vaccine occurred. Local side effects (e.g. pain at the injection site) were the most frequently reported. Immunological results indicate that PepGNP-Dengue can stimulate a specific cellular response against the dengue virus, without producing antibodies.

These results encourage further investigation of this innovative vaccine candidate, and hold promise for other diseases where cellular immunity is important. A potential vaccine for COVID-19, based on the same technology, was also tested by Unisanté on 26 participants. Results are currently being published.